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Serum Creatinine (Substance Concentration)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of creatinine, a waste product from muscle metabolism, in your blood serum. It helps assess kidney function.

Quick summary

["A key indicator of how well your kidneys filter blood."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
9839-2
Short code
RA Nuc Ab Ser Ql ID
Synonyms
RA Nuc Ab Ser Ql ID
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
immune-diffusion
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Is Creatinine?

Creatinine is a natural byproduct of muscle activity and protein breakdown. Healthy kidneys filter it from your blood and remove it from your body through urine. Elevated levels may suggest kidney problems, while lower levels could indicate dehydration or muscle loss.

Why Is This Test Done?

Doctors order creatinine tests to evaluate kidney function, monitor chronic kidney disease, check for dehydration, or assess conditions like heart failure or muscle disorders.

How Is the Test Performed?

A blood sample is drawn from a vein, typically in your arm. The sample is sent to a lab for analysis using an automated method to measure creatinine concentration.

What Do Results Mean?

Results are compared to a reference range specific to your age, sex, and health. Higher-than-normal levels may signal impaired kidney function, while very low levels might indicate conditions like severe dehydration or muscle atrophy.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Creatinine

Frequently asked questions

How often should I get this test?
The frequency depends on your health status. Healthy adults may not need routine testing unless advised by a doctor. People with kidney disease, diabetes, or hypertension may need regular monitoring.
Can diet affect creatinine levels?
Yes, high-protein diets can temporarily raise creatinine levels, as muscle breakdown increases. Hydration also plays a role—dehydration can elevate creatinine.
What if my results are abnormal?
If results are outside the expected range, your doctor may recommend further testing or adjustments to your treatment plan, such as managing medications or dietary habits.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy